cycling between minibuffer and last window|buffer

Question

I'd like to cycle between an active minibuffer window and the last recent buffer.

1  (defun cycle-to-minibuffer-window ()
2    (interactive)
3    (when (active-minibuffer-window)
4      (if (minibuffer-window-active-p (get-buffer-window))
5           (select-window (other-buffer (current-buffer)))
6        (select-window (active-minibuffer-window)))))
7  
8  (global-set-key (kbd "C-<f9>") #'cycle-to-minibuffer-window)

To bad that line 5 (other-buffer (current-buffer)) returns, in this case, the wrong buffer. :(
Which elisp construct could I use instead to get the buffer|window I wanted?

Example (tested with emacs -Q):

1. There are 3 buffers: *scratch*, *Messages* and *Minibuffer-0*.
2. My active buffer is *scratch*. I do find-file aka C-x C-f.
3. Now pressing C-<F9> (calling my function), wants to switch to *Messages* buffer, but *scratch* buffer would be correct.

Answer 1

If you use Icicles then the buffer you want is the value of variable icicle-pre-minibuffer-buffer. It is the buffer that was current before the minibuffer became active."

If you don't use Icicles then you can save this buffer in a variable yourself by adding a function that sets it to minibuffer-setup-hook. E.g.

(defvar my-pre-minibuffer-buffer nil
  "Buffer that was current before the minibuffer became active.")

(defun my-save-pre-buffer ()
  "Set `my-pre-minibuffer-buffer'."
  (setq my-pre-minibuffer-buffer  (my-last-non-minibuffer-buffer)))

(defun my-last-non-minibuffer-buffer ()
  "Return the most recently used non-minibuffer live buffer."
  (catch 'my-last-non-minibuffer-buffer
    (dolist (buf  (buffer-list))
      (when (and (buffer-live-p buf)  (not (minibufferp buf)))
        (throw 'my-last-non-minibuffer-buffer buf)))
    nil))

(add-hook 'minibuffer-setup-hook 'my-save-pre-buffer)

Having this buffer in a global variable means you can access it anytime. E.g.:

(with-current-buffer my-pre-minibuffer-buffer ...)

or

(pop-to-buffer my-pre-minibuffer-buffer)

Answer 2

Another option I've found:

(nth 1 (buffer-list))

The minibuffer will be the 0th one in the buffer-list and the previous buffer is the 1st.

Answer 3

Another solution, which will only work if you use ivy, is to replace line 5 from my question with:

  (select-window (ivy--get-window ivy-last))